# Alternative Method for Determination of Vibroacoustic Material Parameters for Building Applications

## TL;DR

This paper introduces an alternative method to measure material properties for vibration isolation in buildings using image processing and simple tests.

## Contribution

The study proposes a new, image-based method for determining dynamic stiffness and damping as an alternative to traditional techniques.

## Key findings

- Strong correlations were found between relative indentation and dynamic stiffness (10–60 MN/m3).
- Relative rebound showed a strong relationship with damping (6–12%).
- Density and material composition significantly affect critical damping and dynamic stiffness.

## Abstract

The development of urbanization and the resulting expansion of residential and transport infrastructures pose new challenges related to ensuring comfort for city dwellers. The emission of transport vibrations and household noise reduces the quality of life in the city. To counteract this unfavorable phenomenon, vibration isolation is widely used to reduce the propagation of vibrations and noise. A proper selection of vibration isolation is necessary to ensure comfort. This selection can be made based on a deep understanding of the material parameters of the vibration isolation used. This mainly includes dynamic stiffness and damping. This article presents a comparison of the method for testing dynamic stiffness and damping using a single degree of freedom (SDOF) system and the method using image processing, which involves tracking the movement of a free-falling steel ball onto a sample of the tested material. Rubber granules, rubber granules with rubber fibers, and rebound polyurethanes were selected for testing. Strong correlations were found between the relative indentation and dynamic stiffness (at 10–60 MN/m3) and the relative rebound and damping (for 6–12%). Additionally, a very strong relationship was determined between the density and fraction of the critical damping factor/dynamic stiffness. The relative indentation and relative rebound measurement methods can be used as an alternative method to measure the dynamic stiffness and critical damping factor, respectively.